1. Field
Embodiments of the present invention may relate to a home appliance like a washing apparatus, more specifically, to a washing machine having a steam generator and a controlling method of the same, and embodiments of the present invention may relate to a home appliance including a steam generator and a controlling method of the same.
2. Background
The present invention relates to a home appliance, in particular to a washing machine which is a representative example of a home appliance and a dryer is another example. In addition, a washer-dryer having washing and drying functions capable of washing and drying laundry may be an additional example of a home appliance.
Recently, a refresher for refreshing clothes by using heated air or steam, not washing clothes by using water has been released and such a refresher may be an example of the home appliance.
A dishwasher for washing dishes, not clothes, may be also an example of a home appliance in a broad sense. In the present specification, a home appliance includes all kinds of washing apparatuses including all the devices mentioned above.
In this instance, a steam generator provided in such a washing apparatus is a mechanism for generate and supply steam to objects such as clothes or dishes. The steam is employed as a heat source for heating an object and a moisture supply source for supplying moisture to an object. Accordingly, such functions may be expanded and applied to various home appliances as well as a washing apparatus.
The washing machine will be described as representative example of the washing apparatus in the present specification. Unless exclusive and contradictory with the other devices, the present invention may be applicable to the other type washing apparatuses and electric home appliances.
The steam generator is provided in a washing machine and it generates high temperature steam. The steam generator supplies the steam in cycles of washing to improve a washing effect. Also, the steam generator is provided in a washing apparatus having a drying function, namely, a washing apparatus such as a dryer or a refresher and it removes wrinkles and unpleasant smell. Accordingly, the steam generator can be employed as a refresher capable of refreshing clothes to make a user feel like new clothes.
A conventional steam generator for a washing machine according to the prior art will be describe as follows.
FIG. 1 is a perspective view schematically illustrating a structure of a drum washing machine. FIG. 2 is a perspective view schematically illustrating a steam generator according to the prior art. FIG. 3 is a cut-away perspective view of the steam generator shown in FIG. 2, seen at a different another angle.
As shown in FIG. 1, a drum washing machine having a conventional steam generator includes a case 10 for defining an exterior appearance thereof, a cylindrical tub 12 horizontally oriented in the case 10 to hole wash water, a drum 14 rotatably mounted in the tub 12, and a steam generator 16 configured to supply steam to the inside of the drum 14.
In this instance, the drum is an accommodation part for accommodating washing objects, namely, clothes and so on. A drum provided in the dryer may accommodate clothes and so on as drying objects. Similarly, dry clothes are accommodated in an object accommodation part for refreshing. Accordingly, the accommodation part may be expanded and variable according to the appearance thereof, the kind of an object and a function and an appearance of an electric home appliance. In other words, such the accommodation part may be expanded variously to an accommodation part for accommodating dishes, an accommodation part for accommodating clothes to perform refreshing and an inner tub of a pulsator washing machine.
In a front surface of the case 10 is formed an opening 18 in communication with the inner space of the drum to load and unload laundry. A door 20 is rotatable forwardly to open and close the opening 18.
Meanwhile, a water supply valve 22 and a water supply hose 24 are provided in a predetermined portion of the case 10 to supply water to the steam generator 16.
Also, a steam supply pipe is connected to the steam generator 16 as a passage to guide the steam generated in the steam generator 16 into the drum 14 to inject the steam.
Referring to FIGS. 2 and 3, the steam generator 16 will be described in detail as follows.
The steam generator 16 includes a lower case 28 for defining a predetermined space to store water therein, an upper case 30 coupled to a top of the lower case 28 and a heater 32 configured to heat the water stored in the steam generator 16.
In the upper case 30 may be provided a water inlet to supply water to the steam generator from the water supply hose 24 and a steam outlet 36 to exhaust the steam generated in the steam generator 16 to the steam supply pipe 26.
Meanwhile, the heater 32 is mounted in a lower portion of the lower case 28, in parallel to a bottom surface of the lower case 28. When water is supplied to the steam generator 16, the heater 32 is put into operation for heating water in a state of being submerged in the water.
The mounting structure of the heater will be described more specifically as follows.
As shown in FIG. 3, the heater 23 is inserted in the inner space of the rectangular-shaped case through a lateral surface having a small area out of lateral surfaces of the cases 28 and 30, in parallel with the bottom surface of the case. The lateral surfaces are sealed airtight to prevent water leakage and an electric power is supplied to the heater via a terminal 35.
Meanwhile, a bracket 33 is provided on the bottom surface of the lower case 28 and the heater is fixedly inserted in the bracket 33.
Accordingly, an end of the heater 32 is fixed to the bracket 33 and the other end thereof is fixed to a lateral surface of the case.
A water level sensor 40 is provided in a predetermined portion of the upper case 30 to detect a water level of the water stored in the steam generator 16. A temperature sensor 42 is provided in a center portion of the upper case 30 to measure the temperature of the water heated by the heater 32 and the temperature of the steam.
The water level sensor 40 includes a high level electrode bar 40c and a low water level electrode bar 40b for sensing high water levels and low water levels, respectively, and a common electrode bar 40a. In addition, partition walls 45 and 46 may be provided to surround the water level sensor and the partition walls are employed to maintain the sensed water levels and to perform a function of reducing a deviation of sensed levels.
The conventional steam generator having the structure mentioned above will be operated as follows.
First of all, when a washing cycle of the washing machine starts, water is supplied to the inner space of the steam generator 16 via the water inlet 34.
The water drawn into the steam generator 16 is heated by the heater 32 and converted into steam. The steam is drawn into the drum 14 accommodating the washing objects via the steam outlet 36 and it performs wetting and soaking processes for the laundry, to enhance washing efficiency.
In this instance, the steam exhausted via the steam outlet 36 is a high temperature steam. When an exhaustion valve that is able to be open and closed by the pressure of the steam is provided in front or behind the steam outlet, the steam exhausted via the steam outlet may be high temperature and high-pressure steam. However, the steam may be supplied to the drum by the pressure thereof.
Meanwhile, once the wetting and soaking process for the laundry is completed, the operation of the steam generator 16 is completed and a series of cycles are performed to finish the washing of the laundry.
However, the conventional steam generator 16 for the washing machine has a disadvantage of unnecessarily large volume. A large area surface of the heater 32 is installed in parallel with the bottom surface of the lower case 28 and the length of the steam generator 16 cannot help but be increased.
Accordingly, the overall volume of the steam generator 16 is increased only to enlarge the profile of the washing machine. In addition, the production cost happens to arise and it is difficult to apply the steam generator to the other types of washing machines or electric home appliances as well as the washing machine.
Moreover, to install the steam generator having the conventional arrangement of the heater 32 in a washing machine or dryer having a low capacity, the entire profile of the washing machine or dryer has to be enlarged unnecessarily. Also, the unnecessarily large capacity steam generator is installed and the steam generating efficiency might be deteriorated accordingly.
Meanwhile, a water surface is formed broad in the steam generator and the steam or hot water could be supplied to the laundry loaded in the drum 14. Accordingly, damage to fabric of the laundry happens.
Also, bubbles generated by water heating might interfere with the electrode of the water level sensor 40 to generate noise in the signal sensed during the sensing the water level. Accordingly, the water level sensor 40 might be malfunctioned.
The steam generator 16 has following structural disadvantages.
As shown in FIG. 3, the water level sensor 40 senses the high water level (A) and the low water level (B) to protect the steam generator from the overheating of the heater. In this instance, the heater starts heating at the high water level (A) and stops the heating at the low water level (B). Accordingly, it can be said that the water filled with a predetermined space (C) between the high water level (A) and the low water level (B) is changed into steam. However, the water heated to generate the steam includes the water filled with the space (D) to the low water level (B). The water filled with the space (D) is heated but not changed into steam. Accordingly, energy and water waste might be generated. In other words, all of the water inside the steam generator is heated to protect the heater but not be changed into steam, such that energy and water waste might be generated.
Also, the heater has to be installed, spaced apart a predetermined distance from a lower surface of the lower case, because the quantity of heat transmitted to the lower case from the heater has to be reduced in case of overheating. Accordingly, a large amount of water might be wasted unnecessarily to satisfy the heater protection water level.
Such heater protection water level means too much capacity of the steam generator mentioned above and it means that it takes a long time to generate the steam. In other words, the heater protection water level means that it takes a long time to generate the steam after the heating starts and that it takes a long time to perform a steam cycle.
For example, it is a recent trend to shorten the duration time of the washing, with enhancing washing efficiency. For example, a washing course proposes that it should be 50 minutes to finish a final drying-spinning cycle after a washing cycle of the washing course starts. In such a washing course, the washing cycle may be performed proximately for 10 to 15 minutes. However, it takes quite a lot of time for the steam generator mentioned above to generate the steam and it is difficult to apply the steam to such washing course. That is because the washing cycle could finish just when the steam starts to be supplied after water is heated.
Of course, it is possible to apply the steam cycle during the washing cycle composing such the washing course. However, in this instance, that steam cycle might lengthens the overall washing cycle and the time taken to perform the washing course might be lengthened. Accordingly, the user has to endure the long time of the washing course after adding the steam cycle.
Meanwhile, the steam generator 16 has to sense the low water level (B) or the heater protection water level precisely to prevent the overheating of the heater, such that re-water supply and heater control may be enabled.
However, the algorithm for sensing the water level could be complex and the structure of the partition wall 45 and 46 is required. The water level sensor, the structure for sealing the heater bracket 45 and with the heater to fix the heater, the plastic injection molding case 28 and 30 which can endure the high temperature and the capacity of the steam generator might increase the production cost of the steam generator disadvantageously.
Moreover, there is limitation on expanding the heat generation area because the heater 32 is installed adjacent to the bottom surface of the steam generator. Accordingly, heat efficiency deterioration might be generated by scale as the heater 32 is used. Especially, the water is getting close to the low water level, water splashing might be generated near the heater and the heated water, not the steam, might be supplied to the inside of the drum.
Also, the heater 32 is directly submerged in the water and there is concern of heater corrosion. To solve such heater corrosion, the heater 32 has to be formed of a stainless material and the unit cost of production might be increased.
Meanwhile, there is a pipe type steam generator that generates steam by heating the water flowing along a passage, not by heating the accommodated water. Such a pipe type steam generator is disclosed in U.S. Pat. No. 7,913,339A, EP 2287390A1, and International Publication No. WO2008/014924A1. However, such the pipe type steam generator has to change water into steam by heating flowing water. Accordingly, the amount of the supplied water and the amount of the steam has to be limited. In other words, when too much water is supplied via a passage, a predetermined amount of the supplied water might be supplied to an object accommodation part, failing to be changed into steam. Accordingly, clothes might be damaged. Because of such limitation, the water supply time and the amount of the supplied water cannot help but be substantially short and small in the pipe type steam generator. Accordingly, the water supply and the heating have to be performed by the heater quite often disadvantageously.
Specifically, the amount of the flowing water or the time of the water supply has to be controlled for outlet of pure steam in the pipe type steam generator. In the prior applications mentioned above, a flow controller for measuring a flow rate is necessary to control the amount of the flowing steam, or an algorithm for measuring the water supply time is necessarily provided. To provide the flow controller for measuring the flow rate, the configuration of the steam generator has to be complex and control components have to be quite complex. When the flow rate is controlled by the flow controller, the water pressure might be decreased. When the flow rate is controlled by the water supply time, the reliability of the flowing amount supplied according to the water pressure of a water supply source might be deteriorated.
Also, the pipe type steam generator converts the water flowing along the passage into steam. Accordingly, the passage has to be relatively narrow and scale might accumulate on the passage only to cause a problem of plugged passage occasionally. To solve the problem, an auxiliary algorithm for removing the scale can be embodied. However, there is limitation on the user's implementing such algorithms one by one. That is because a steam cycle is not always implemented in an electric home appliance, especially, a washing machine or dryer.
Such the pipe type steam generator basically performs water supplying and heating at the same time. Accordingly, to enable the steam generator to supply pure steam water supply has to be performed intermittently, not continuously. Because of that, steam supply has to be performed intermittently. In other words, it is difficult to supply a large amount of steam continuously and there is a problem of deteriorated efficiency for water supplying and heating to supply steam accordingly. That is because steam has to be supplied to an entire area inside the drum, not to a specific area, in a washing machine or a dryer.